FR2504441A1 - INDUSTRIAL ROBOT HAVING MULTIPLE ROTATION AXES - Google Patents

Abstract

INDUSTRIAL ROBOT WITH SEVERAL AXES OF FREE MOVEMENT AND INCLUDING AN ARM SUPPORTING WORK ORGANS 24, MOUNTED IN A MANNER TO BE ABLE TO PIVOT ON THE END OF A SUPPORT COLUMN 14 SO AS TO ALLOW ANGULAR MOVEMENT AROUND AN 18 HORIZONTAL AXIS FROM A HORIZONTAL MIDDLE ANGULAR POSITION, THE ANGULAR POSITIONING OF THE SUPPORT ARM 16 BEING CONTROLLED BY A LIFTING CYLINDER 32 HAVING AN END CONNECTED SO AS TO BE ABLE TO PIVOT IN RELATION TO THE AUDIT SUPPORT ARM IN A REMOTE POSITION OF THE said HORIZ AX 18 ANGULAR DISPLACEMENT, WHILE ITS OTHER END IS CONNECTED TO BE PIVOTABLE WITH RESPECT TO THE SUPPORT COLUMN 14.

Description

The present invention relates to an industrial robot comprising several

  axes of freedom of movement and more particularly a control system for movement

  vertical lifting of the robot working arm.

  Industrial robots are working machines intended to move a head or a working tool in a controlled manner to bring it into any position in a predetermined operating or working area and to give a desired orientation to the head

  or with the work tool In general, the head carrying the

  it can move along two or three coordinate axes

  data in space and can also be oriented following

  with two or three angular coordinate systems Therefore industrial robots usually have

  four, five or six independent axes of movement, including

  each mandated by an actuation device Many

  its kinematic structures have already been proposed in order to obtain all the desired movements and, in general, these

  structures obtain the desired result thanks to a

  combination of linear and angular displacements While the linear displacements are generally obtained by means of carriages controlled by hydraulic or electropneumatic cylinders for example of the type having a screw and a guide nut, to obtain the angular displacements a wide variety of devices, such as chains and chain wheels, worm reduction gears, reduction gears known as

  trade name "Harmonic Drive" and the like.

  A very common type of industrial robot comprises a column mounted on a fixed base for a translational or rotational movement and supporting an oscillating arm movable around a horizontal axis in order to perform a

  lifting movement In turn, this arm supports a cha-

  riot allowing to obtain a third linear displacement-

  area and on which is mounted a tool holder head.

  However, the actuating devices used -2 until now for obtaining the lifting movement of the swinging arm are not entirely satisfactory, mainly by the fact that the drive torque applied to the swinging arm to make it pivot about its axis. horizontal rotation must overcome a moment

  very high inertia due to the presence of devices

  laterally heavy carried by the swinging arm at a distance

  considerable tance of its axis of rotation This problem is further complicated by the fact that this distance is variable and that consequently the moment of inertia also varies

  when moving the carriage along the swing arm.

  It is for this reason that the classified devices

  actuation sics such as worms and

  worm grenages as well as other conventional devices using gears, which act with an arm transmitting a weak force to the organs to be

  are not able to guarantee the accuracy re-

  quise in a work robot of the type used in the

of modern industry.

  This is why an object of the present invention

  is to provide an industrial robot of the type described above

  above, which is equipped with means for controlling the

  lifting movement of the swinging arm so as to

  rer a precise position of the latter even if it is loaded

  managed by heavy organs distant from the axis of rotation of the arm and even if the moment of inertia acting on the arm varies as a result of the movement of the carriage along said arm. Another object of the present invention is to

  supply an industrial robot with means of

  command of the swing arm lifting movement and which is particularly resistant to wear and consequences

  wear on positioning accuracy.

  Another object of the present invention is to

  provide an electromechanical actuation device

  being part of the movement control means

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  swing arm lifting ment in the industrial robot

of the type described above.

  The present invention provides an industrial robot

  with several axes of freedom of movement and com-

  carrying an arm supporting working members and mounted so as to be able to pivot on the upper end

  a support column so as to allow movement

  angular around a horizontal axis from a horizontal mean angular position, characterized in that the angular positioning of the support arm is controlled by a lifting cylinder, one end of which is connected so as to be able to pivot on the arm of support in

  a position distant from the horizontal axis of the movement an-

  gular, and the other opposite end of which is connected

  in order to be able to pivot to the support column.

  The lifting cylinder can be a lifting device

  electromechanical operation which, in accordance with

  invention, comprises a threaded spindle mounted so that it can rotate, at its two opposite ends, in bearings connected to each other by

  rigid walls constituting at least one guide member

  linear dage, a guide nut meshing with the threaded spindle and being equipped with at least one projecting appendage

  intended to contact, with possibility of sliding, the

  linear guide gane, and an outer casing tu-

  bulaire rigidly fixed to said projecting appendage

  the guide nut and having at least one end device

  mite allowing a connection with possibility of pivoting

said support arm.

  A form of realization will now be described.

  preferential sation of the invention using an example

  ple and with reference to the accompanying drawings, in which: FIG. 1 is a side elevation view

  schematic of an industrial robot according to the invention.

  Figure 2 is an axial sectional view of the

  mechanical lifting rinse used in the robot

  -4- Figure 1; and your figure 3 is a cross-sectional view

  taken along line III-III of Figure 2.

  Figure 1 shows the industrial robot con-

  form of the invention in solid lines in its neutral or inactive position This robot carries a tool-carrying head, intended for example for welding. For further details concerning the tool-carrying head, reference may be made to the Italian patent application no. 68 126-A / 77 filed on May 19, 1977 by the Applicant To give a more complete illustration of the kinematic mechanism of the robot, the oscillating support arm of the robot has been shown in broken lines in a raised position and

  in a lowered position Naturally, apart from the ope-

  welding ration, this robot can also be used for other purposes, for example to handle parts

to be machined or the like.

  As shown in Figure 1, the robot is mounted on a fixed base 10 via

  a support column 14 which can be driven in rotation

  tation by drive devices not shown.

  However, the support column 14 can also be mounted so as to be driven in translation on the

  base 10 by means of suitable guide rails, not

  presented Base 10 rests on the ground by means of feet

adjustable 12.

  An oscillating support arm 16 is mounted on the ex-

  upper end of the support column 14 so

  to allow angular displacement around a horizontal axis

  zontal de rotatîon 18 The oscillating support arm 16 comprises a cradle and guide rails or slides for a carriage 20 mounted so as to be able to move in linear translation along these slides Su-r one end of the carriage 20 is mounted a tool holder head 22 having several degrees of freedom of movement, for example as described in the patent application mentioned previously The tool supported by the head 22 z L Jz O 4 1 - may for example be constituted by pliers weld

  classics 24 with electric resistance Electric current

  stick is sent to the welding tongs 24 by means of

  diary of a head 22, from a rotating field transformer 26 supplied by flexible shielded cables

  from 28, as described in said patent application

vet cited.

  To achieve controlled positioning of the arm

  of oscillating support 16 in order to bring it into the posi-

  angular position desired, the present invention provides a linear actuation device constituted by a jack

  electromagnetic 32, one end of which is connected in a

  lesson to be able to swivel to a console 30 projecting

  on one side of the support column 14 The electro-

  mechanical 32 is driven by an electric motor 34, which is fixed to the jack and which will be described below so

  more detailed The opposite end of the real electromechanical N

  pic 32 is connected so that it can pivot at 36 to the oscillating support arm 16 at a predetermined distance

of its axis of rotation 18.

  The actuating device 32 is arranged relative to the support column 14 and to the oscillating support arm 16 so that the reaction points of the

  forces transmitted between these three organs during the

  arm 16 are located at the vertices of a triangle which, although its shape changes during the rotation of arm 16, will nevertheless have approximately equal sides so that the force of delivery or pressure

  exerted by the actuating device 32 will remain in per-

  approximately equal to the weight of the carrying head

  tool 22 and tool 24 carried by the latter.

  Although the actuating device 32 can be of different types and although it can be for example a hydraulic cylinder or the like, according to the invention this device is of the electromagnetic type as will be described below This type of device

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  guarantees the maximum rigidity of the actuating device

  ment under the action of a compression load at which

  he is submissive in some of his work positions.

  Referring now to Figures 2 and 3, we see * that an actuating device according to the preferred embodiment of the invention comprises a plate provided with pivots 42 allowing a connection, with

  possibility of oscillation, console 30 on the colon-

  support 14 (Figure 1) and serving as the basis for an organ-

  tubular 44 fixed to the plate 40 by a ring 46 which can be welded in position The electric motor 34, represented in FIG. 1, is fixed laterally to the plate 40 The end of the tubular member 44 opposite

  to the one adjacent to the engine, is fitted with a

  closure cap 48, and both plate 40 and

  closing cap 48, are fitted with bearings respectively

  tifs 50 and 52, allowing movement, with the possibility of rotation, of the two ends of a threaded spindle or worm screw 54, one end of which extends beyond the plate 40 and carries a pulley 56 driven by the motor 34 of Figure 1, via a

toothed belt 35.

  The electric motor 34 can be a DC collector motor or an AC induction motor and is precisely controlled from a

  manner known per se by nu-

  such as a process computer, not shown

smelled.

  The assembly formed by the plate 40, the tu-

  bular 44 and the cap 48 therefore defines a

  rigid housing in which the threaded pin 54 is mounted

  ted so as to be able to pivot The housing thus defined

  contains a guide nut 58 meshing with the file spindle

  tee 54 and fitted with projecting appendages or diametrically opposite keys 60 and 62 and fixed in position by screws 63 and projecting from the member

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  tubular 44 through longitudinal slots 64 and 66

  arranged for this purpose in this organ Preferably the

  seems the guide nut 58 and the threaded spindle 54 is constituted by a unit comprising a guide nut and a worm containing circulating balls, as is known in the art, so as to improve

  positioning accuracy and reduce wear.

  The keys 60, 62 of the guide nut 58 are

  fixed with screws 67 to an outer casing tu-

  ball 68 extending coaxially to the threaded spindle 54

  and closed at its distal end by a cover

  key 70 preferably welded to said envelope and equipped with projecting connection appendages 72 allowing a

  connection, with swiveling possible, to the support arm

  oscillating port 16 of FIG. 1, by means of a pin 74 The tubular external envelope 68

  has a sliding ring at one end

  health 76 mounted so that it can slide over the

  face of the tubular member 44 and, at its other end, the closure cap 48 comprises a disc 78 fixed to the

  cover by screws 49 and fitted with a seal

  frame 82 intended to serve as a guide for the displacement of the tubular outer envelope 68, and simultaneously

sealing piston.

  As will be evident from the

  description above, when the pulley 56 pivots, the guide nut 58 moves along the threaded spindle or the worm screw 54 with balls and shifts the outer tubular casing 68 which is guided on the ring 76 and the disc

  78 which serve as sliding bearings, so as to modify

  the distance between the points of the pivotal connections

  tants 42 and 74 of the actuator Preferably

  this the end of the tubular outer casing 68 is

  hooked up to plate 40 using protective bellows

tion 80.

  It is obvious that the structure described possesses

  2 c 104441 8- of great rigidity owing to the large distance existing between the support points of the casing 68 and that its rigidity will be substantially preserved even in

  the maximum extension position of the actuating device

  Furthermore, the perimeter of the support surface has a large diameter so that the support force is distributed with a low unit load and with

  a geometric configuration avoiding bending.

  According to another characteristic before-

  tagger of the invention, as represented by the

  seal 82 in FIG. 2, the envelope ex-

  tubular taper 68 and tubular member 44 form

  seems a piston and cylinder device, in which the air located in the space between the disc 78 and

  the cover 70 is subjected to compression or to a

  latation in accordance with the contraction or extension of the actuating device For this purpose, a calibrated hole 88 is provided in the cover 70 so that this effect can be used to achieve shock absorption during

  the operation of the actuation device, in particular

  tie when an engine suddenly breaks down, so

  ere to slow the free movement of the guide nut As an additional safety device intended to prevent a free fall of the oscillating support arm 16

  in the event of a failure of the motor 34, a set of res-

  Belleville 84 and 86 shock absorber spells are fitted to each

  end of threaded spindle 54.

  Although we have described in detail

  but illustrated in the accompanying drawings a form of realization

  preferred position of the invention, it will be understood that the latter is not limited to this precise form and that

  many obvious changes and modifications to the specifications

  technical specialists can be brought there without

  from the scope of the present invention.

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Claims (4)

  1. Industrial robot having several axes of free movement and comprising an arm supporting working members (24), mounted so as to be able to pivot on the end of a support column (14) so   to allow angular displacement around an axis ho-   rizontal (18) from a median angular position   horizontal, characterized in that the positioning an-   support arm (16) is controlled by a lifting cylinder (32) having one end connected so as to be able to pivot, relative to said support arm in   a position distant from said horizontal axis (18) of the displacement   angular cement, while its other end is re-   linked so that it can rotate relative to the column support (14).   2. Industrial robot according to claim 1, characterized in that the average length of the vage cylinder (32) is approximately equal to the distance between the horizontal axis (18) of the angular displacement and the connection point with pivoting of the cylinder lifting column (14) and the connection point with   pivoting of the lifting cylinder (32) to the support arm (16).   3 Industrial robot according to claim 1, characterized in that the lifting lever (32) comprises a threaded spindle (54) mounted at its two opposite ends in bearings connected to each other by rigid walls forming at least one linear guide member, a guide nut (58) meshing with the spindle   threaded (54) and being fitted with at least one appendage.   projection (60,62) intended to contact with possibility of sliding the linear guide member, and a tubular outer casing (68) fixed to said projecting appendage (60,62) of the guide nut (58) and comprising, on the 'one of its ends, means (72,74) of connection with   pivoting on the support arm (16). 04441   - 4 Industrial robot according to claim 3, characterized in that the guide nut (58) meshing   with the threaded pin (54) is coupled to it with the interpo-   sition of circulating beads. Industrial robot according to claim 3, characterized in that one of the bearings (48,52) of the threaded spindle (54) is produced in the form of a piston connected in leaktight manner to said outer tubular casing (68 ) and that the latter has a background   equipped with a calibrated hole (88) communicating with the atmos-   sphere. 6 As an application of the robot according to one   of the preceding claims, a device for actuating   electromechanical molar, characterized in that it comprises a cylinder constituted by a threaded spindle (54) and a guide nut (58) moving on said spindle, the ends of which rotate in bearings (50,52) connected to one another by walls rigid concentric (44,68) forming a linear guide member, said nut carrying projecting appendages (60,62) which can slide in said guide member (44) and the outer tubular casing (68) fixed to these appendages and having at   less at one of its ends, means (72,74) allow   both the articulated connection to a swing arm (16) supporting working bodies.